Device for measuring the motion of a conducting body through magnetic induction

Abstract

A device for measuring a motion of a moving electrically conducting body is disclosed. A magnetic field generated by, for example, electromagnets or permanent magnets, penetrates at least a partial area of the moving body. Two or more measuring devices are arranged outside the magnetic field to measure a measurement magnetic field that is induced by electrical currents in the moving body. The measuring devices are arranged essentially symmetrically with respect to the magnetic field generating means or the moving body. The measurement magnetic field represents at least one motion variable of the moving body. The measuring device is thereby no longer subjected to the temperature-dependent variations of the exciting field.

1. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body;  
 at least two measuring devices arranged on opposite sides of the moving body and outside the magnetic field of the magnetic field generating means, for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body,  
 wherein the at least two measuring devices are constructed so as to produce identical measurement signals for a motion of the moving body performed in an identical manner.  
 
   
   
     2. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body;  
 at least two measuring devices arranged on opposite sides of the moving body and outside the magnetic field of the magnetic field generating means, for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body,  
 wherein the at least two measuring devices are arranged essentially symmetrically with respect to the magnetic field generating means or the moving body.  
 
   
   
     3. The device of  claim 2 , and further comprising at least two pairs of measuring devices that are arranged on opposite sides of the moving body, wherein the at least two pairs are arranged in the motion direction on opposite sides of the magnetic field generating means. 
   
   
     4. The device of  claim 2 , and further comprising first magnetic flux guiding means associated with the at least two measuring devices for guiding the measurement magnetic field. 
   
   
     5. The device of  claim 4 , and further comprising second magnetic flux guiding means associated with the magnetic field generating means for guiding the measurement magnetic field. 
   
   
     6. The device of  claim 4 , wherein the first magnetic flux guiding means are made at least predominately of a material comprising iron powder or a ferritic magnetic material. 
   
   
     7. The device of  claim 5 , wherein at least one of the first and second magnetic flux guiding means form a closed magnetic circuit. 
   
   
     8. The device of  claim 5 , wherein the first magnetic flux guiding means and the second magnetic flux guiding means are formed separate of each other. 
   
   
     9. The device of  claim 5 , wherein the first magnetic flux guiding means and the second magnetic flux guiding means are formed at least partially in common. 
   
   
     10. The device of  claim 5 , wherein the first and second magnetic flux guiding means are made of material selected from the group having a high electrical conductivity, a high magnetic conductivity, low eddy current losses and a low noise. 
   
   
     11. The device of  claim 5 , wherein the first and second magnetic flux guiding means are made substantially of a soft magnetic material. 
   
   
     12. The device of  claim 5 , wherein at least one of magnetic permeability and eddy current losses of the second magnetic flux guiding means are higher than corresponding magnetic permeability and eddy current losses of the first magnetic flux guiding means. 
   
   
     13. The device of  claim 2 , and further comprising second magnetic flux guiding means associated with the magnetic field generating means for guiding the measurement magnetic field. 
   
   
     14. The device of  claim 13 , wherein the second magnetic flux guiding means comprise soft iron. 
   
   
     15. The device of  claim 13 , wherein in the motion direction, the at least one measuring device is arranged adjacent to the second magnetic flux guiding means with an offset thereto. 
   
   
     16. The device of  claim 13 , wherein the at least one measuring device is arranged in the motion direction at least partially within the second magnetic flux guiding means and offset from the magnetic field generating means comprising at least one permanent magnet. 
   
   
     17. The device of  claim 2 , wherein the magnetic field generating means comprises at least one permanent magnet having opposite magnetic poles facing each other, with the moving body moving between the magnetic poles. 
   
   
     18. The device of  claim 2 , wherein the at least one measuring device includes at least one magnetic field sensor selected from the group consisting of Hall sensor, a magneto-resistive sensor and field plate. 
   
   
     19. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body;  
 at least two measuring devices arranged on opposite sides of the moving body and outside the magnetic field of the magnetic field generating means, for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body,  
 wherein the measurement signals of the at least two measuring devices are superimposed with an identical polarity, and wherein interfering signals caused by changes in distance between the moving body and the measuring devices are superimposed with an opposite polarity.  
 
   
   
     20. The device of  claim 19 , wherein the at least two measuring devices are electrically connected with opposite polarity. 
   
   
     21. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body;  
 at least two measuring devices arranged on the same side of the moving body and outside the magnetic field of the magnetic field generating means, for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body,  
 wherein the measurement signals of the at least two measuring devices are superimposed with an identical polarity, and wherein interfering signals caused by changes in distance between the moving body and the measuring devices are superimposed with an opposite polarity.  
 
   
   
     22. The device of  claim 21 , wherein the at least two measuring devices are electrically connected with opposite polarity. 
   
   
     23. The device of  claim 21 , wherein the at least two measuring devices are arranged essentially symmetrically with respect to the magnetic field generating means or the moving body. 
   
   
     24. The device of  claim 21 , wherein the at least two measuring devices are constructed so as to produce identical measurement signals of an identical motion of the moving body. 
   
   
     25. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body;  
 at least one measuring device arranged outside the magnetic field of the magnetic field generating means and having at least one induction coil for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body; and  
 at least one magnetically conducting termination element arranged on end faces of the at least one induction coil.  
 
   
   
     26. The device of  claim 15 , wherein the magnetic field generating means, at least one of the measuring devices, or the termination element are at least one of secured and thermally coupled to an associated support or a to common support. 
   
   
     27. The device of  claim 26 , wherein the associated or common support is made of a metal with a good thermal conductivity. 
   
   
     28. A device for measuring a motion of a moving body having a motion direction and at least one region that is electrically conducting, comprising:
 magnetic field generating means for producing a magnetic field, which penetrates at least one spatially limited partial area of the at least one electrically conducting region of the moving body; and  
 at least two measuring heads, each having at least one measuring device for measuring a measurement magnetic field that is induced by electrical currents in the at least one electrically conducting region of the moving body, with the measurement magnetic field representing at least one motion variable of the moving body,  
 wherein the at least one measuring device is arranged outside the magnetic field of the magnetic field generating means, and  
 wherein the magnetic field generating means are arranged diametrically opposed with respect to the rotation axis.  
 
   
   
     29. The device of  claim 28 , wherein the magnetic field generating means produce a magnetic field that penetrates the electrically conductive region of the moving body in a partial area that is contiguous in the motion direction of the moving body.